Black Tank Flush

When you look down the toilet, are you sure that there is a lot of water down there? Open the valve by pulling the correct handle and see if anything comes out. If little comes out, close valve and dump five gallons of water down the toilet if it can take it. Now open the valve and see if five gallons comes out. If little comes out, you have a blockage or the valve is not opening. Repair valve or find the blockage. Sometimes the plastic disk from cutting the hold falls inside the tank when built. One possible solution is to push a hose up into the tank and turn on the water to flush. None of what I am saying is pretty, wear your bio-hazard suit or ask a septic pumping business if they can pump out the tank first.